A radiation detector can include a plastic scintillator, such as BC-704™-brand scintillator available from Saint-Gobain Crystals of Hiram, Ohio, USA. The BC-704™-brand scintillator includes alternating layers of wavelength shifting fibers and phosphorescent materials. FIG. 1 includes a cross-sectional view of a conventional radiation sensor 10 that includes layers of phosphorescent material 122 that includes 6LiF and silver doped ZnS (ZnS:Ag). In another scintillator, copper doped ZnS (ZnS:Cu) may be used instead of ZnS:Ag. Scintillating light from the phosphorescent material 122 passes through a clear epoxy 126 and is received by rectangular-shaped wavelength shifting fibers 124. A reflector 140 surrounds the combination of the phosphorescent material 122, the wavelength shifting fibers 124, and the clear epoxy 126 as illustrated in FIG. 1 to increase the amount of scintillating light received by the wavelength shifting fibers 124. The scintillating light is shifted to light of a longer wavelength and transmitted to a photosensor (not illustrated) that converts light received by the photosensor to an electronic signal. Further illustrated in FIG. 1 is a neutron moderator 160 that converts fast neutrons to thermal neutrons to increase the likelihood of capture by the phosphorescent material 122. The radiation sensor 10 can be in the form of a rectangle, and another scintillator can be in the form of a disk.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.